Electronic devices such as personal computers, laptops, cell phones, personal digital assistants, headsets, game systems, and cameras may be equipped with one or more radio transceivers for wireless exchange of information. A radio transceiver may use a method known as frequency hopping to reduce interference with other electronic devices by changing from one carrier frequency to another during a transmission. A frequency hopping transceiver transmits a related group of data packets over many carrier frequencies selected from a list of radio frequencies referred to as a channel mask. The list of carrier frequencies in a channel mask is negotiated between a transmitting electronic device and a receiving electronic device so that both devices can exchange signals on a same carrier frequency at the same time. Frequency hopping transceivers known in the art, for example frequency hopping transceivers operating in accord with the Bluetooth open wireless communications protocol, each have a single channel mask for coordinating radio communications.
A carrier frequency included in a channel mask may also be referred to by a corresponding channel number. After a data packet is transmitted and successful receipt of the data packet is acknowledged, the frequency hopping transceiver in a transmitting electronic device changes to a next channel number selected from its channel mask, the receiving device changes to the same channel number as the transmitting electronic device, and another data packet is transmitted. The steps of selecting a channel number from the channel mask, transmitting a data packet on the selected channel number, receiving the data packet on the same channel number, and selecting a new channel number are repeated until all data packets in a data set have been successfully transmitted from the transmitting electronic device and received by the receiving electronic device.
Compared to a frequency hopping transceiver, which switches from one channel to another during transmission and reception of a data set, a single frequency radio transceiver transmits and receives data packets on a single carrier frequency. Single frequency transceivers are commonly used in electronic devices adapted for communicating over wireless local area networks. The carrier frequency used by a single frequency transceiver may be selected from a range of carrier frequencies specified in one of the protocols defined in IEEE 802.11, such as 802.11b, 802.11g, or 802.11n. Some electronic devices may include both a single frequency transceiver and a frequency hopping transceiver. For example, a game console having both a frequency hopping transceiver and a single frequency transceiver may transmit data packets related to sound effects, music, or speech to a headset equipped with a frequency hopping transceiver while simultaneously exchanging other data packets over a wireless local area network (WLAN) with a router having a single frequency transceiver.
Frequency hopping transceivers operating in accord with the Bluetooth open wireless communications protocol and single frequency transceivers operating in accord with IEEE 802.11 share a range of transmission and reception frequencies in the 2.4 gigahertz (GHz) Industrial, Scientific, and Medical (ISM) band. Radio frequency interference is likely to occur between collocated single frequency and frequency hopping transceivers known in the art. Interference between collocated single frequency and frequency hopping transceivers may cause some data transmitted over a WLAN to be retransmitted, resulting in a reduced rate of data communication over the WLAN. In some cases, WLAN communications may be severely disrupted, causing a loss in utility in an electronic device with collocated single frequency and frequency hopping transceivers.
Methods such as Adaptive Frequency Hopping (AFH) and Packet Traffic Arbitration have been used to reduce data communication errors in electronic devices with collocated radio transceivers. In AFH, a set of channel numbers corresponding to carrier frequencies available for transmission and reception of data packets is negotiated between a frequency hopping transceiver in a transmitting electronic device and a frequency hopping transceiver in a receiving electronic device. A set of negotiated channel numbers is referred to as a hop set, a channel mask, or an AFH mask. The channel numbers in an AFH mask may be chosen to leave a selected magnitude of frequency separation between the AFH mask and a blocking signal, for example a carrier frequency used by a single frequency transceiver such as a WLAN transceiver. Also, transmitting and receiving electronic devices using AFH to communicate with each other use a same method for selecting a sequence of channel numbers from a channel mask in each device so that both devices communicate over the same channel number at the same time.
Packet Traffic Arbitration (PTA) may reduce communication errors by providing means for deciding when a frequency hopping transceiver or a single frequency transceiver in an electronic device has access to shared radio resources. For example, PTA may give priority to the frequency hopping transceiver for some operations and to the single frequency transceiver for other operations. Reception of data packets by one collocated system may be prevented while the other collocated system is transmitting, so PTA may result in a reduction of the overall data transfer rate and may therefore be unacceptable for systems in which communications latency, especially latency in WLAN communications, is undesirable.
What is needed is a system and method for operating collocated single frequency and frequency hopping transceivers without reducing a rate of WLAN data communication. What is further needed is a system and method for operating collocated single frequency and frequency hopping transceivers without controlling access to shared radio resources by PTA.